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ntfs_compr.c revision 1.5 
      1 /*	$NetBSD: ntfs_compr.c,v 1.5 2009/03/18 16:00:21 cegger Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1998, 1999 Semen Ustimenko
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  *
     28  *	Id: ntfs_compr.c,v 1.4 1999/05/12 09:42:54 semenu Exp
     29  */
     30 
     31 #include <sys/cdefs.h>
     32 __KERNEL_RCSID(0, "$NetBSD: ntfs_compr.c,v 1.5 2009/03/18 16:00:21 cegger Exp $");
     33 
     34 #include <sys/param.h>
     35 #include <sys/systm.h>
     36 #include <sys/namei.h>
     37 #include <sys/proc.h>
     38 #include <sys/kernel.h>
     39 #include <sys/vnode.h>
     40 #include <sys/mount.h>
     41 #include <sys/buf.h>
     42 #include <sys/file.h>
     43 #include <sys/malloc.h>
     44 
     45 #include <miscfs/specfs/specdev.h>
     46 
     47 #include <fs/ntfs/ntfs.h>
     48 #include <fs/ntfs/ntfs_compr.h>
     49 
     50 #define GET_UINT16(addr)	(*((u_int16_t *)(addr)))
     51 
     52 int
     53 ntfs_uncompblock(
     54 	u_int8_t * dbuf,
     55 	u_int8_t * cbuf)
     56 {
     57 	u_int32_t       ctag;
     58 	int             len, dshift, lmask;
     59 	int             blen, boff;
     60 	int             i, j;
     61 	int             pos, cpos;
     62 
     63 	len = GET_UINT16(cbuf) & 0xFFF;
     64 	dprintf(("ntfs_uncompblock: block length: %d + 3, 0x%x,0x%04x\n",
     65 	    len, len, GET_UINT16(cbuf)));
     66 
     67 	if (!(GET_UINT16(cbuf) & 0x8000)) {
     68 		if ((len + 1) != NTFS_COMPBLOCK_SIZE) {
     69 			dprintf(("ntfs_uncompblock: len: %x instead of %d\n",
     70 			    len, 0xfff));
     71 		}
     72 		memcpy(dbuf, cbuf + 2, len + 1);
     73 		memset(dbuf + len + 1, 0, NTFS_COMPBLOCK_SIZE - 1 - len);
     74 		return len + 3;
     75 	}
     76 	cpos = 2;
     77 	pos = 0;
     78 	while ((cpos < len + 3) && (pos < NTFS_COMPBLOCK_SIZE)) {
     79 		ctag = cbuf[cpos++];
     80 		for (i = 0; (i < 8) && (pos < NTFS_COMPBLOCK_SIZE); i++) {
     81 			if (ctag & 1) {
     82 				for (j = pos - 1, lmask = 0xFFF, dshift = 12;
     83 				     j >= 0x10; j >>= 1) {
     84 					dshift--;
     85 					lmask >>= 1;
     86 				}
     87 				boff = -1 - (GET_UINT16(cbuf + cpos) >> dshift);
     88 				blen = 3 + (GET_UINT16(cbuf + cpos) & lmask);
     89 				for (j = 0; (j < blen) && (pos < NTFS_COMPBLOCK_SIZE); j++) {
     90 					dbuf[pos] = dbuf[pos + boff];
     91 					pos++;
     92 				}
     93 				cpos += 2;
     94 			} else {
     95 				dbuf[pos++] = cbuf[cpos++];
     96 			}
     97 			ctag >>= 1;
     98 		}
     99 	}
    100 	return len + 3;
    101 }
    102 
    103 int
    104 ntfs_uncompunit(
    105 	struct ntfsmount * ntmp,
    106 	u_int8_t * uup,
    107 	u_int8_t * cup)
    108 {
    109 	int             i;
    110 	int             off = 0;
    111 	int             new;
    112 
    113 	for (i = 0; i * NTFS_COMPBLOCK_SIZE < ntfs_cntob(NTFS_COMPUNIT_CL); i++) {
    114 		new = ntfs_uncompblock(uup + i * NTFS_COMPBLOCK_SIZE, cup + off);
    115 		if (new == 0)
    116 			return (EINVAL);
    117 		off += new;
    118 	}
    119 	return (0);
    120 }
    121